The correct answer is B) the force that keeps people connected.
The title of the story, "Gravity," most likely represents the force that keeps people connected.
That is what the story really represents and what the title of the story projects. Although gravity is the force of nature that allows existence on planet Earth, in the story it can be understood as the force that joins people in difficult times and gives sense to many moments in people's lives; what keeps humans connected and show endurance.